Apparently, Porsche will not take this car to Le Mans. It's been build exclusively for the American Le Mans series.
I read some articles in the german press and the situation seems to be as follows:
Although the car was build in Germany, the whole LMP2 project was initiated and launched by Porsche of North America. The Porsche factory itself will not run the car, for 2006 it will be runned exclusively by the Penske Team in the ALMS, so if Penske doesn't plan to go to Le Mans as well, we won't see this car at the Sarthe next year. However, after 2006 Porsche plans to sell this car also to other teams, so we can expect to see one 2007 at the latest